ATP-binding cassette transporter A1 (ABCA1) is an membrane protein,using ATP for transferring substances,modulated by liver X receptors(LXRs), retinoic X receptors(RXRs), sterol regulatory element binding proteins(SREBPs), microRNAs and other upstream modulators.ABCA1 plays an important role in multiple pathways related to lipid accumulation.Upregulating ABCA1 expression may slow-down lipid accumulation, thus offers a promising strategy for metabolic diseases.

Objective: To explore the efficacy of open reduction and internal fixation in the treatment of senile osteoporotic ankle fractures. Methods: A retrospective case series study was conducted to analyze the data of 26 elderly patients with osteoporotic ankle fractures which all caused by sprain from June 2012 to June 2018 in Changhai Hospital, including 10 male and 16 female patients aged from 60 to 93 years (mean, 69.72 years). In these 26 patients, three had medial malleolus fractures, four had lateral malleolus fractures, six had double ankle fractures and 13 had cotton's fractures. According to the Lauge-Hansen type, all 26 patients can be classified into four types: 5 with supination external rotation type, 4 supination adduction type, 16 with pronation-external rotation type and 1 with pronation abduction type. All the patients received open reduction and internal fixation. Plate fixation was used for lateral and posterior malleolus fractures, plate fixation and cannulated screws were applied to fix the comminuted posterior malleolus fracture while in the comminuted internal malleolus fracture, the steel plate was used only when needed. Early professional functional rehabilitation training and active anti-osteoporosis treatment were applied. All the operation time and bleeding volume were recorded, and the reduction of fracture plus the healing of wounds were observed. At last follow-up, American Orthopedic Foot & Ankle Society (AOFAS) Ankle Hindfoot Scale was used to evaluate the treatment effect and the Visual Analogue Scale (VAS)to evaluate the therapeutic effect and the subjective satisfaction of the patients. Complications were recorded as well. Results: All patients were followed up for 12-48 months (mean, 23.6 months). Operation time ranged from 30 to 95 minutes (mean, 70 minutes) and bleeding volume ranged from 10 to 150 ml (mean, 70 ml). All patients got satisfied reduction of fracture within 25 patients' incision healing in first intention, although one has fat liquefaction. AOFAS Ankle Hindfoot Scale improved from preoperative (84.4±10.8)points to (31.9±11.4)points at last follow-up (P<0.01), and the results were excellent in five patients, good in 17, fair in three and poor in one, with the excellent and good rate of 85%. VAS improved from preoperative(1.85±0.73)points to (9.23±0.28)points at last follow-up (P<0.01). Among 26 patients, 5 with ankle stiffness of different degree recovered after rehabilitation care, and 2 with internal malleolus fractures had bone displacement when receiving rehabilitation care, with no side effect on basic function. No serious complications such as wound infection or skin necrosis were found. Conclusion For osteoporotic ankle fractures in the elderly, open reduction and internal fixation can promote functional recovery and relieve pain.